snapped off both motormount bolts flush on my engine block.
currently designing/modifying mounts to be able to handle the downward stress and take the load off those bolts.
this will be the 4th try.
does anybody have a photo or two showing how they did it?
as always thanks!

timothale

12-26-2012 07:41 AM

need picts

I looked at your project picts but no mounts shown, On the last SBF swap I did, I used maverick V8 mounts and made a bracket to use front to back bolts like most chevy mounts. I did a search for maverick V 8 motor mounts and got several images. the ink line drawing showed the 6038 ones I used.

Irelands child

12-26-2012 11:07 AM

I use all ARP bolts - never a problem. BUT - I have torn the so called bonded elastomer, made-in-Korea crap apart. Now I drill through the entire assembly, add two Gr8 5/16 or 3/8" bolts just snugged to the metal and use a nyloc nut. Solved that problem by limiting the travel compression/rebound. As far as adding any vibration - haven't noticed.

The new motor mounts - actually found some Trade # 2257/NAPA#602-1151 made in the USA replacements which are used in most Fords through '72.

timothale

12-26-2012 02:19 PM

no thru rivet

I thought the factory spec was for a thru rivet like your bolts to prevent full separation.

hcompton

12-26-2012 05:53 PM

You can usally buy solid mounts for ford mustangs and fox body cars. Rubber mounts let your engine get leverage and then snap the mounts. Also check the trans mount if its wasted it can put pressure on the other mounts. A solid trans mount or one from energy suspension made out of neopreme will help keep things in line.

Lots of hp may require a turn buckle or even a chain to hold it in place. Turnbuckle kits are easy to hide and will hold the engine agaisnt the frame. Front mount engine plate mount will also resolve the issue.

hcompton

12-26-2012 06:06 PM

Quote:

Originally Posted by timothale
(Post 1627257)

I thought the factory spec was for a thru rivet like your bolts to prevent full separation.

Those are probably after market. Some also have a cage that will hold the mount at max stretch.

But once they are stretching they will break at some point.

66GMC

12-26-2012 10:07 PM

I was a Ford partsman and HAD a 351C in a 68 Torino which used the early "sandwich" style mount, and pulled many of the FORD ones (presumably built in NA) apart, which always resulted in the fan blade cutting through the upper rad hose. :pain:

I drilled and bolted them also ... and never noticed any vibration issues.

Since working for NAPA, I began to notice pictures of motor mounts and similarities in design..

the earlier failures were the steel itself cracking/splitting.
yes i measured the holes for depth.
i replaced the bolts with hex heads that are supposed to be a bit stronger than grade 8's
the photos will show why the previous bolts failed.
they couldnt stand up to the leverage.http://i98.photobucket.com/albums/l2...ps7065ce01.jpg

I don't like the biscuit type mounts, they worked on 40's fords because the enclosed drive line -torque tube tied the engine-trans and rear end all together. The out rigger angle iron style will work on a chevy because they have 3 bolts spaced far enough apart to spread out the leverage. I prefer the mount shown in the last picture, more compact and it HAS the safety rivet . The middle one with the safety strap just doesn't look neat enough when you can see everything. I would build new frame brackets to weld to the frame and use the ones in the last pict. All the leverage would be transferred to the frame which should be boxed from the firewall foreward at least when doing a swap.

timothale

12-27-2012 08:21 AM

mount picts

A couple weeks a go Newinteriors posted picts of some mounts he built for his C cab wagon project. I don't know how to link you to the picts but if you do a search her on HR for new interiors motor mounts you can see his. they are fancier than I build but an idea of what will work best. He also posted picts another time of the plane jane type.

hcompton

12-27-2012 12:51 PM

Have you tried removing the rubber disc and replacing it with washers or some other solid disc so the mount cant lift and get at and angle that will allow pressure to be put on the mounts. I am thinking the breakage is from the entire thing moving once the top lifts the strain on the engine side that is solid mounted and snaps the bolts.

That mount is also not strong enough for Heavy duty use. I would do a turnbukle off one of the head bolts.

Grade 8 bolts dont break in line. What i am saying is that a large bolt like that will with stand more than the metal thats holding it if you were just pulling straight against it but since your force is a prying force it can lean the bolt side ways and it will snap right off. Softer bolts will hold up longer. Arp might have something they can recommend that can with stand the lateral force applied.

Did the ends of the bolts come out of the block. Grade 8 bolts can be hard to drill. If you must drill get some good reverse cut drill bits. They should spin the bolts out while your drilling once you take the center out of the bolt.

last silly question did the bolts break on the side pulling up or the side pushing down?

Hope some of this helps. All else fails... 1/4 inch steel plate mount to the front of the motor will keep it in place. This how nascar engines are mounted. Also most purpose built race cars.

carolinacustoms

12-27-2012 02:51 PM

What if you welded an angle brace to your current mounts that would bolt to the frame and essentially traingulate the current mounts you have already made and take away the up/down twisting that is breaking the bolts? You could also use the same type of rubber spacer for vibration where the brace bolts to the frame if that is a concern. But it would greatly strengthen your current mounts and eliminate the movement that is causing you problem without having to completely redesign anything. Also I highly recommend the bolt through the mounts as otehrs or atleast a chain from the driver side head to the frame to limit torque twist. Just a thought.

geezer69

12-27-2012 05:14 PM

i did my 65-66 mustang mounts just like irlelands child does. never had another problem.

timothale

12-28-2012 07:39 AM

motor mounts

Detroit did a lot of work designing motor mounts, I was there 15 years. I always try to use the basic factory design when doing an engine swap. Get a speedway catalog and see what they offer. The old Hurst style mounts, outrigger style is one piece that bolts to BOTH sides of the engine. I don't like them when using a modern transmission that has a rear transmission mount, the motor mounts at the front and back are too far apart and creats too much stress. Speedway builds a crosmember that you can use the mounts shown in the earlier picts 66 GMC posted The weight of the engine -force is down , NOT leverage shearing the block bolts. speedway also sells universal brackets you can weld to your frame for the factory mount. 910-1831. I have always built my own but I have lathe, mill, plasma, torchmate pattern style cutter, etc. factory style mounts with the safety strap or THRU safety rivet don't require a chain and turnbuckle for a street car. In the 60's the GM motor mounts would tear apart and the engine would move over on the steering shaft rag joint and you couldn't turn the steering wheel. GM got a lot of bad press when they had to send a crew to repair the POPES Caddy limo.

unclebill

12-29-2012 09:33 AM

since i have the shop to myself today.
i am going to try and fab up some of these